You dont have javascript enabled! Please enable it! MCQ in Power Transmission and Distribution Part 2 | REE Board Exam

# MCQ in Power Transmission and Distribution Part 2 | REE Board Exam

This is the Multiple Choice Questions Part 2 of the Series in Electric Power Transmission and Distribution System Engineering as one of the Electrical Engineering topic. In Preparation for the REE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electrical Engineering field, Electrical Engineering Books, Journals and other Electrical Engineering References.

#### Continue Practice Exam Test Questions Part 2 of the Series

Choose the letter of the best answer in each questions.

51. Insulators used for transmission line at the dead-end tower are

a. suspension type

b. shackle type

c. strain type

d. pint type

Solution:

52. Economic studies have shown that D.C. transmission is cheaper than a. c transmission for lengths

a. a. below 300 km

b. beyond 600 km

c. beyond 1200 km

d. less than 100 mile

Solution:

53. Transmission voltages in the range 230 kV – 765 kV are known as

a. High voltage

b. Extra High Voltage

c. Ultra High Voltage

d. Very High Voltage

Solution:

54. Which one of the following statements is false? As the transmission voltage increases,

a. Corona loss increase

b. Conductor copper loss decreases

c. Cost of insulators, transformers, switches & circuit breakers increases

d. Corona loss decreases

Solution:

55. The internal inductance of a solid conductor of radius r and carrying a current I is equal to

a. 0.5I x 10-7 H/m

b. 0.5I x 10-7 exp(-1/4) x r H/m

c. 0.5 x 10-7 H/m

d. 1.5 I x 10-7 exp(-1/4) x r H/m

Solution:

56. Which one of the following statements is not true?

a. The GMD method of finding inductance does not apply to ACSR conductors

b. Current density in ACSR conductors is not uniform due to skin effect

c. The GMD between two circular areas, each of different diameters, is equal to the distance between their centers.

d. ACSR is better than TZACSR

Solution:

57. Expanded ACSR conductors are used

a. To increase the tensile strength of the line

b. To reduce corona loss

c. To reduce I2R loss

d. To minimize galloping

Solution:

58. A conductor with 19 strands, each of same diameter and each having an inductance of L Henries is used for a transmission line. The total inductance of the conductor will be

a. L

b. L/361

c. 19L

d. L/19

Solution:

59. In a double-circuit line with hexagonal spacing ,

a. The phases are balanced, but the conductors of each individual phase are not balanced.

b. The conductors of each individual phase are balanced , but the phases are not balanced

c. The phases, and the conductors of each individual phase are both balanced

d. Is better for High voltage

Solution:

60. Which one of the following statements is true?

a. Skin effect at 50 Hz is negligible for larger diameter conductors but becomes appreciable for smaller conductor.

b. Skin effect at 50 Hz is negligible whatever the diameter of the conductor.

c. Resistivity of soil does not have any effect on zero sequence resistance

d. Skin effect at 50 Hz is negligible for the smaller diameter conductors but becomes appreciable for the larger conductor conductor.

Solution:

61. Which one of the following statements is true?

a. Resistance of a conductor decreases and the internal inductance increases as the frequency is increased

b. Resistance and internal inductance of a conductor both increase with increase of frequency

c. At UHV the line is inductive

d. Resistance of a conductor increases and the internal inductance decreases as the frequency is increased

Solution:

62. The surge impedance of a double-circuit power transmission line is

a. 40 ohms

b. 200 ohms

c. 400 ohms

d. 800 ohms

Solution:

63. The surge impedance of a telephone line is

a. 50 ohms

b. 75 ohms

c. 200 ohms

d. 400 ohms

Solution:

64. Bundle conductors are preferred in EHV transmission lines because

a. It is easy to fabricate thin conductors and combine them to make a bundle

b. Inductance of the line is reduced, and the corona loss, and radio & TV interference is minimized.

c. Tower height is reduced and hence transmission cost is low.

d. Preferred by power system planning

Solution:

65. The percentage regulation of an overhead transmission line can be zero when the load power factor is

a. Lagging

b. Unity

d. zero

Solution:

66. Which one of the following statements is true?

a. Skin effect increases the resistance of a conductor ,but proximity effect decreases the resistance

b. Both skin effect and proximity effect increase the resistance of a conductor

c. Both skin effect and proximity effect increase the internal inductance of a conductor

d. Proximity effect is not consider in Medium voltage application

Solution:

67. A transmission line having parameters A1, B1, C1, D1 is in parallel with another having parameters A2, B2, C2, D2. The overall ” A ” parameter of the combination is

a. A1A2 +B1C2

b. (A1B2 +A2B1)/(B1+B2)

c. C1+C2 + (A1-A2)(D2-D1)/(B1+B2)

d. A1A2 +C1C2

Solution:

68. Handling of the telephone receiver may become dangerous due to _______ from a power line

a. Electromagnetic induction

b. Electrostatic induction

c. Both electromagnetic and electrostatic induction

d. Cross talk effect

Solution:

69. Mutual inductance between a three -phase power line and a telephone line due to third harmonic current in the power line is

a. The algebraic sum of mutual inductances from individual phase wires

b. The arithmetic sum of mutual inductances from individual phase wires

c. Zero

d. Always positive

Solution:

70. Which one of the following statements is true?

a. For 11 kV insulators, the ratio of wet spark-over voltage to working is zero

b. For 66 kV insulators, the ratio of dry spark-over voltage to working voltage is 8.3

c. For 11 kV insulators, the ratio of dry spark-over voltage to working voltage is 3.3

d. For 11 kV insulators, the ratio of dry spark-over voltage to working voltage is 8.3

Solution:

71. In a suspension insulator, the mechanical stresses on the conductor are

a. Increased

b. Reduced

c. The same

d. zero

Solution:

72. The string efficiency of the insulator can be increased by

a. Increasing the number of strings in the insulator

b. Increasing the ratio , capacitance to earth/capacitance per insulator

c. By the correct grading of various capacitances

d. Decreasing the number of strings

Solution:

73. The potential across insulator discs can be equalized by having

a. The same capacitance for each unit

b. The highest capacitance for the lowest unit and decreasing progressively the capacitance of other units

c. The lowest capacitance for the lowest unit and increasing progressively the capacitance of other units

d. Many insulator disc

Solution:

74. If the voltage applied to the core and sheath of a cable is halved , the reactive power generated by the cable will be

a. Halved

b. 1/4 th of the original value

c. doubled

d. The same

Solution:

75. If C1 is the capacitance between any two cores of a 3-core cable, and C2 is the capacitance between any core and the sheath, then the measured value of the capacitance between any two cores with the third core isolated is equal to

a. C1C2/(2C1+C2)

b. 0.5(3C1+C2)

c. 3C2

d. C1

Solution:

76. Sheaths are provided in cables to

a. Provide proper insulation

b. Provide mechanical strength

c. Prevent ingress of moisture

d. Prevent irregularities in harmonics

Solution:

77. Which one of the following statements is true? In a protection scheme for a communication line,

a. The lightning arrester prevents any accumulation of static charge , and the drainage coil relieves the system of any excess voltage

b. The lightning arrester relieves the system of any excess voltage , and the drainage coil prevents any accumulation of static charge

c. The lightning arrester prevents any accumulation of static charge on the communication circuit

d. It has no effect

Solution:

78. In a lightly loaded transmission line of such a length that the capacitive reactance is appreciable, the receiving end voltage

a. Is always less than the sending end voltage

b. May exceed the sending end voltage

c. Is always equal to the sending end voltage

d. zero

Solution:

79. The size of conductor on modern EHV lines is obtained based on:

a. Voltage drop.

b. permeability density.

c. Corona.

d. Skin effect

Solution:

80. Ferranti effect on long overhead lines is experienced when it is:

b. On full load at unity p.f.

c. On full load at 0.8 p.f. lag.

d. In all these cases.

Solution:

81. The presence of earth in case of overhead lines:

a. Increases the capacitance.

b. Increases the inductance.

c. Decreases the capacitance.

d. Decreases the inductance.

Solution:

82. Effect of increase in temperature in overhead transmission lines is to:

a. Increase the strength and length.

b. Decrease the strength and length.

c. Decrease the stress but increase the length.

d. None of these.

Solution:

83. The Self GMD method is used to evaluate:

a. Inductance.

b. Capacitance.

c. Inductance and Capacitance both.

d. None of the above of the overhead transmission lines.

Solution:

84. Sheaths are used in cables to:

a. Provide proper insulation.

b. Provide mechanical strength.

c. Prevent ingress of moisture.

d. None of these.

Solution:

85. A short length of cable between the dead end tower and the power transformer:

a. Always reduces the steepness of the incident wave.

b. Reduces the steepness of the wave under certain conditions only.

c. It does not change the steepness.

d. Degrease the creepage distance

Solution:

86. Corona loss is less when the shape of the conductor is:

a. Circular.

b. Flat.

c. Oval.

d. Independent of shape.

Solution:

87. Corona loss increase with:

a. Increase in supply frequency and conductor size.

b. Increase in supply frequency and reduction in conductor size.

c. Decrease in supply frequency and conductor size.

d. Decrease in supply frequency but increase in conductor size.

Solution:

88. In order to eliminate sheath losses, a successful method is:

a. To transpose the cable along with cross bonding.

b. Transpose the cables only.

c. Cross bonding the cables is enough.

d. None of the above is effective.

Solution:

89. For effective use of a counterpoise wire:

a. Its leakage resistance should be greater than the surge impedance.

b. Its leakage resistance should be less than the surge impedance.

c. Its leakage resistance should be equal than the surge impedance.

d. The two resistances may have any relation.

Solution:

90. In EHV transmission lines, efficiency of transmission can be increased by decreasing the corona loss. This is achieved by:

a. Increasing the distance between the line conductors.

b. Using bundled conductors.

c. Using thick conductors.

d. Using thin conductors.

Solution:

91. Arcing on transmission lines is prevented by connecting a suitable:

a. Circuit breaker.

b. Protective relay.

c. Inductor in the neutral.

d. Capacitor in the neutral.

Solution:

92. The chief advantage of using high tension alternating current for power transmission over long distances is that.

a. Power is transmitted with a minimum of line losses.

b. Aluminum is available for that specific design

c. There will be no insulation

d. Counterpoise is no longer used

Solution:

93. When a lightning wave arrives at an open end, what happens?

a. it is divided by two at that point

b. it doubles that point

c. it passes to the air

d. it is dissipated

Solution:

94. The most economical size of a feeder is that size for which the annual cost of energy lost in the feeder equals the cost of interest and depreciation on the capital cost of the conductor material.

a. Kirchoffโs Law

c. Law on Economics

d. Kelvinโs Law

Solution:

95. When alternating current is passing through a conductor there is a tendency to the current to crowd near the surface of the conductor. This is known as

a. corona

b. magnetization

c. skin effect

d. resistivity

Solution:

96. When alternating current is passing through a parallel conductor there is a tendency that there will exist an induced current between the surface of the conductor. This is known as

a. edge effect

b. proximity efect

c. skin effect

d. Kelvin effect

Solution:

97. The two conductors of a single phase transmission line suspended in air carry currents in opposite direction. The force per unit length on each conduct or varies:

a. directly as the distance between the conductors

b. directly as the current in either conductor

c. directly as the square of the current in either conductor

d. inversely as the square of the distance between the conductors

Solution:

98. A medium length transmission line problem can be solved using the _______circuit.

a. exact equivalent

b. nominal wye

c. nominal T

d. any of these

Solution:

99. The advantage of using static capacitor to improve the power factor is because they

a. are most loss free

b. provide continuous charge of power factor

c. none of these

d. are not variable

Solution:

100. The insulation strength of an power cable in transmission line is described as its

a. basic insulation strength

b. basic impulse stress

c. basic impulse insulation level

d. basic insulation factor

Solution:

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